The present invention relates to the field of construction machines, in particular to a device for determining the temperature of a road building material, such as asphalt, bitumen, asphalt blend material or the like, newly applied by a construction machine, in particular a road finishing machine, in a mounting width, the device being arranged at the construction machine in a region within the mounting width and the device comprising an infrared temperature measuring head, a motor and a controller, the infrared temperature measuring head being arranged to be twistable by the motor transverse to the direction of travel of the construction machine and being effective to record temperature measuring values of the surface of the road building material during a rotational movement at at least two measuring points spaced apart from one another.
Furthermore, the present invention relates to a construction machine comprising such a device.
With road building projects, such as building a new road or renewing damaged road surfaces, the quality of the newly applied road building material is to be documented by the executing companies using check tests. Measuring the temperature of the asphalt layer directly after being mounted by the road finishing machine is among these tests. The temperature of the newly applied road building material is measured over the entire mounting width directly behind the asphalt plank of the road finishing machine.
A lane temperature monitoring system comprising a temperature sensor is known from WO 2000/70150 A1. The temperature sensor here may either by a thermal-imaging camera, a thermal scanner or a thermal-imaging camera operating in a “line scan” mode. The temperature sensor is arranged at the back end of a road finishing machine such that the entire width of the newly applied asphalt layer is scanned. The recorded temperature values may be displayed graphically on a display device.
Disadvantages with such a temperature sensor is the fact that a thermal-imaging camera or thermal scanner is usually very expensive to buy. In particular, for smaller building companies such an investment usually cannot be realized due to the high costs. Furthermore, it is disadvantageous that the detection or opening angles of a thermal-imaging camera or a thermal scanner are highly limited such that, with mounting or installation widths in a range of 8 to 12 meters, for example, a correspondingly adapted objective lens has to be applied at the thermal-imaging camera in order to be able to detect the entire mounting width of the newly applied road building material. This, in turn, increases the cost of such a temperature sensor further. Alternatively, both the thermal-imaging camera and the thermal scanner would have to be applied in a correspondingly elevated position at the road finishing machine, i.e. a lot more than four meters above the surface of the newly applied road building material, in order to be able to detect the entire mounting width of the newly applied road building material. However, this is of particular disadvantage when passing below bridges.
However, when mounting the thermal-imaging camera or thermal scanner at the road finishing machine in an advantageous region of 3 to 4 meters above the surface of the newly applied road construction material, due to the limited detection or opening angle, a correspondingly flat fitting angle relative to the surface of the newly applied road building material is necessitated (cf. FIG. 2, large fitting angle γF) in order for the entire mounting width of the newly applied road building material to be detected. However, the temperature of the newly applied road building material over the entire mounting width is not measured directly behind the asphalt plank of the road finishing machine but in a correspondingly large distance to the back edge of the asphalt plank. Consequently, the temperature values measured no longer correspond to the actual values in the region directly behind the asphalt plank.
A device, as described above, for measuring the temperature of the surface of hot asphalt, including an infrared temperature measuring head moving transverse to the direction of travel, a motor for moving this sensor and a controller, is known already from DE 20 2009 016 129 U1.
Based on this device, calculating the mounting width of the newly applied asphalt layer is known from DE 20 2013 001 597 U1. Same is calculated using the height of the measuring head above the asphalt layer, which is determined using a distance sensor, and the angle values where the measuring head changes its direction of movement.
When recording the temperature measuring values by means of the known device, however, the result is not a steady measuring point pattern. When the fitting position and/or the fitting angles of the device change, so does the distance between the measuring points on the surface of the newly applied road building material. In addition, the distance between the measuring points in the direction of travel of the construction machine changes with a changing speed of travel of the construction machine. If same moves faster, the distance between the measuring points in the direction of travel will become larger.
Consequently, an object of the invention is to provide a simple and cheap device allowing temperature measuring values of newly applied road building material to be recorded over a large mounting width in a region directly behind a construction machine, in particular behind an asphalt plank of a road finishing machine, in a steady measuring point pattern.